My buddy and I were tuning up my jenky old mountain bike with some new parts. Everything is back in place but when I'm riding in my top gear the pedals skip about a quarter turn every half to full rotation while climbing/accelerating. Everything seems to be fine in my other working gears and it doesn't do it if i'm cruising or pedaling downhill.

We've been trying to adjust the tension just right because it almost feels like the chain keeps slipping off the end but the last couple hours have made us think otherwise.